The History of Creation, Vol. 2 (of 2) / Or the Development of the Earth and its Inhabitants by the Action of Natural Causes

by Ernst Haeckel

The third great division of the palæontological history of development is formed by the secondary epoch, or the era of Pine Forests, which is also called the mesolithic or mesozoic epoch. It extends from the end of the Permian system to the end of the Chalk formation, and is again divided into three great periods. The stratified systems deposited during this period are, first and lowest, the Triassic system, in the middle the Jura system, and at the top the Cretaceous system. The average thickness of these three systems taken together is much less than that of the primary group, and amounts as a whole only to about 15,000 feet. The secondary epoch can accordingly in all probability not have been half so long as the primary epoch.

Just as Fishes prevailed in the primary epoch, Reptiles predominated in the secondary epoch over all other vertebrate animals. It is true that during this period the first birds and mammals originated; at that time, also, there existed important amphibious animals, especially the gigantic Labyrinthodonts, in the sea the wonderful sea-dragons, or Halisaurii, swam about, and the first fish with bones were associated with the many primæval fishes (Sharks) and enamelled fish (Ganoids) of the earlier times; but the very variously developed kinds of reptiles formed the predominating and characteristic class of vertebrate animals of the secondary epoch. Besides those reptiles which were very nearly related to the present living lizards, crocodiles, and turtles, there were, during the mesolithic period, swarms of grotesquely shaped dragons. The remarkable flying lizards, or Pterosaurii, and the colossal land-dragons, or Dinosaurii, of the secondary epoch, are peculiar, as they occur neither in the preceding nor in the succeeding epochs. The secondary epoch may be called the era of Reptiles; but on the other hand, it may also be called the era of Pine Forests, or more accurately, of the Gymnosperms, that is, the epoch of plants having naked seeds. For this group of plants, especially as represented by the two important classes—the pines, or Coniferæ, and the palm-ferns, or Cycadeæ—during the secondary epoch constituted a predominant part of the forests. But towards the end of the epoch (in the Chalk period) the plants of the pine tribe gave place to the leaf-bearing forests which then developed for the first time.

SURVEY
Of the Palæontological Periods, or of the Greater Divisions of theOrganic History of the Earth.
I. First Epoch: Archilithic Era. Primordial Epoch.
(Era of Skull-less Animals and Forests of Tangles.)
1.	Older Primordial Period	or	Laurentian Period.
2.	Middle Primordial Period	”	Cambrian Period.
3.	Later Primordial Period	”	Silurian Period.
II. Second Epoch: Palæolithic Era. Primary Epoch.
(Era of Fish and Fern Forests.)
4.	Older Primary Period	or	Devonian Period.
5.	Mid Primary Period	”	Coal Period.
6.	Later Primary Period	”	Permian Period.
III. Third Epoch: Mesolithic Era. Secondary Epoch.
(Era of Reptiles and Pine Forests.)
7.	Older Secondary Period	or	Trias Period.
8.	Middle Secondary Period	”	Jura Period.
9.	Later Secondary Period	”	Chalk Period.
IV. Fourth Epoch: Cænolithic Era. Tertiary Epoch.
(Era of Mammals and Leaf Forests.)
10.	Older Tertiary Period	or	Eocene Period.
11.	Newer Tertiary Period	”	Miocene Period.
12.	Recent Tertiary Period	”	Pliocene Period.
V. Fifth Epoch: Anthropolithic Era. Quaternary Epoch.
(Era of Man and Cultivated Forests.)
13.	Older Quaternary Period	or	Ice or Glacial Period.
14.	Newer Quaternary Period	”	Post Glacial Period.
15.	Recent Quaternary Period	”	Period of Culture.
(The Period of Culture is the Historical Period, or the Period of Tradition.)

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STRATA CONTAINING PETRIFICATIONS.

Rock-Groups.		Systems.		Formations.		Synonyms of Formations.
V. Quaternary Group, or Anthropolithic (Anthropozoic) groups of strata.		XIV. Recent (Alluvium)		36.	Present	Upper alluvial
				35.	Recent	Lower alluvial
		XIII. Pleistocene (Diluvium)		34.	Post glacial	Upper diluvial
				33.	Glacial	Lower diluvial
IV. Tertiary Group, or (Cænozoic) groups of strata.		XII. Pliocene (Late tertiary)		32.	Arvernian	Upper pliocene
				31.	Sub-Appenine	Lower pliocene
		XI. Miocene (Late tertiary)		30.	Falunian	Upper miocene
				29.	Limburgian	Lower miocene
		X. Eocene Old tertiary)		28.	Gypsum	Upper eocene
				27.	Nummulitic	Mid eocene
				26.	London clay	Lower eocene
III. Secondary Group, or Mesolithic groups of strata		IX. Cretaceous		25.	White chalk	Upper cretaceous
				24.	Green sand	Mid cretaceous
				23.	Neocomian	Lower cretaceous
				22.	Wealden	The Kentish Weald
		VIII. Jura		21.	Portlandian	Upper oolite
				20.	Oxfordian	Mid oolite
				19.	Bath	Lower oolite
				18.	Lias	Lias formation
		VII. Trias		17.	Keuper	Upper trias
				16.	Muschel-kalk	Mid trias
				15.	Bunter sand	Lower trias
II. Primary Group, or Palæolithic (Palæozoic) groups of strata		VI. Permian		14.	Zechstein	Upper Permian
				13.		Lower Permian
		V. Carbonic (coal)		12.	Carboniferous sandstone	Upper carbonic
				11.	Carboniferous limestone	Lower carbonic
		IV. Devonian (Old red sandstone)		10.	Pilton	Upper Devonian
				9.	Ilfracombe	Mid Devonian
				8.	Linton	Lower Devonian
I. Primordial Group, or Archilithic (Archizoic) groups of strata		III. Silurian		7.	Ludlow	Upper Silurian
				6.	Llandovery	Mid Silurian
				5.	Llandeilo	Lower Silurian
		II. Cambrian		4.	Potsdam	Upper Cambrian
				3.	Longmynd	Lower Cambrian
		I. Laurentian		2.	Labrador	Upper Laurentian
				1.	Ottawa	Lower Laurentian

The fourth main division of the organic history of the earth, the tertiary epoch, or era of Leafed Forests, is much shorter and less peculiar than the three first epochs. This epoch, which is also called the cænolithic or cænozoic epoch, extended from the end of the cretaceous system to the end of the pliocene system. The strata deposited during it amount only to a thickness of about 3,000 feet, and consequently are much inferior to the three first great groups. The three systems also into which the tertiary period is subdivided are very difficult to distinguish from one another. The oldest of them is called eocene, or old tertiary; the newer miocene, or mid tertiary; and the last is the pliocene, or later tertiary system.

The whole population of the tertiary epoch approaches much nearer, on the whole as well as in detail, to that of the present time than is the case in the preceding epochs. From this time the class of Mammals greatly predominates over all other vertebrate animals. In like manner, in the vegetable kingdom, the group—so rich in forms—of the Angiosperms, or plants with covered seeds, predominates, and its leafy forests constitute the characteristic feature of the tertiary epoch. The group of the Angiosperms consists of the two classes of single-seed-lobed plants, or Monocotyledons, and the double-seed-lobed plants, or Dicotyledons. The Angiosperms of both classes had, it is true, made their appearance in the Cretaceous period, and mammals had already occurred in the Jurassic period, and even in the Triassic period; but both groups, the mammals and the plants with enclosed seeds, did not attain their peculiar development and supremacy until the tertiary epoch, so that it may justly be called after them.